OMG/Assets/Scripts/OptionMenu.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Audio;
using UnityEngine.UI;

public class OptionMenu : MonoBehaviour
{
    //Resolution
    Resolution[] resolutions;
    public Dropdown resolutionDropdown;

    private void Start() {
        resolutions = Screen.resolutions;
        resolutionDropdown.ClearOptions();

        List<string> options = new List<string>();

        int currentResIndex = 0;

        for (int i = 0; i < resolutions.Length; i++) {
            string option = resolutions[i].width + " x " +  resolutions[i].height;
            options.Add(option);

            if(resolutions[i].width == Screen.currentResolution.width && resolutions[i].height == Screen.currentResolution.height) {
                currentResIndex = i;
            }
        }

        resolutionDropdown.AddOptions(options);
        resolutionDropdown.value = currentResIndex;
        resolutionDropdown.RefreshShownValue();
    }

    public void setResolution(int resolutionIndex) {
        Resolution resolution = resolutions[resolutionIndex];
        Screen.SetResolution(resolution.width, resolution.height, Screen.fullScreen);
    }

    //Audio
    public AudioMixer mixer;

    public void SetMainVolume(float mainVolume) {
        mixer.SetFloat("mainVolume", mainVolume);
    }
    public void SetMusicVolume(float musicVolume) {
        mixer.SetFloat("musicVolume", musicVolume);
    }
    public void SetSfxVolume(float sfxVolume) {
        mixer.SetFloat("sfxVolume", sfxVolume);
    }

    //Quality
    public void setQuality(int qualityIndex) {
        QualitySettings.SetQualityLevel(qualityIndex);
    }

    //Fullscreen
    public void setFullscreen(bool isFullscreen) {
        Screen.fullScreen = isFullscreen;
    }
}